Certain substituted nitro or dinitro-amino pyridines

ABSTRACT

NITROAMINOPYRIDINES AND THEIR USE AS HERBICIDES.

United States Patent Officc 3,634,439 Patented Jan. 11, 1972 3,634,439 CERTAIN SUBSTITUTED NITRO R DINITRO- AMINO PYRIDINES Karl Ayad, Wrexham, Wales, assignor to Monsanto Chemicals Limited, London, England No Drawing, Filed Apr. 2, 1969, Ser. No. 812,890 Claims priority, application Great Britain, Apr. 5, 1968, 16,436/68 Int. Cl. 007d 31/44 US. Cl. 260-295 AM 3 Claims ABSTRACT OF THE DISCLOSURE Nitroaminopyridines and their use as herbicides.

wherein R is selected from the group consisting of halogen, alkyl having a maximum of six carbon atoms, trichloromethyl, trifluoromethyl, alkenyl having a maximum of four carbon atoms, hydroxy, alkoxy having a maximum of six carbon atoms, mercapto, alkylthio having a maximum of six carbon atoms, cyano, carboalkoxy having a maximum of six carbon atoms and sulfino; R and R are each independently selected from the group consisting of hydrogen, alkyl having a maximum of four carbon atoms, 'alkanoyl having a maximum of six carbon atoms, alkylsulfonyl having a maximum of four carbon atoms and phenylsulfonyl; n is an integer 0 to 2; x is an integer 1 to 2; provided that when NR R is in the 2-position, N0 is in the 3-position and R is hydrogen or in the 5-position then R, and R are each selected from the group consisting of hydrogen, acyl having a maximum of six carbon atoms, alkylsulfonyl having a maximum of four carbon atoms and phenylsulfonyl PIOfVlClCCl that both R and R are not hydrogen;

(b) Addition salts of the compounds defined in (a), said addition salts being selected from the group consisting of hydrochlorides, hydrobromides, oxalate, sulfate, benzenesulfonate and the alkyl halides having a maximum of four carbon atoms; and

(c) The N-oxide of the compounds defined in (a).

The preferred compounds of this invention are the pyridine lbases defined in section (a) above.

Preferred compounds are also compounds of the formula NOB):

wherein R is selected from the group consisting of alkyl having a maximum of four carbon atoms and halogen; R is hydrogen and R is selected from the group consisting of acyl having a maximum of four carbon atoms and phenylsulfonyl.

Still further preferred compounds are of the formula wherein R is alkyl having a maximum of four carbon atoms; R is selected from the group consisting of hydrogen, alkanoyl having a maximum of six carbon atoms, alkyl'sulfonyl having a maximum of four carbon atoms and phenylsulfonyl n and x are each integers 1 to 2, provided that when R is hydrogen and n and x are both 1 then R is in a position other than the 5-position.

The preparation of the nitroaminopyridine of this invention are by conventional means, such as the action of fuming nitric acid on the corresponding aminopyridine in the presence of concentrated sulfuric acids. The reaction may initially result in the formation of the nitroamino pyridine which rearranges to the nitroaminopyridine compound.

The addition salts are easily prepared by the reaction of the base with the desired acid or alkyl halide.

Preparation of the N-oxide compounds is by the oxidation of the base with perbenzoic acid.

The aminopyridines are prepared by the known process of preparing aromatic amines. These methods include but is not limited to the degradation of amides and the amination of the pyridine derivative with sodamide.

Preparation of other derivatives is illustrated by the following examples:

EXAMPLE 1 This example describes the preparation of 5-nitro-6- methyl-Z-acetamidopyridine.

A mixture consisting of 10 grams 5-nitro-6-methyl-2- aminopyridine, 37 ml. glacial acetic acid and 37 ml. acetic anhydride Was heated at reflux temperature for 4 hours. After cooling to room temperature, the liquid was added to crushed ice and the acid neutralized with solid sodium bicanbonate. The solid which separated was removed by filtration, washed with a small amount of water and dried. Recrystallization from an ethanol-Water solution gave a solid melting at 195 C.

Calcd. for C H N O (percent): C, 49.3; H, 4.61; N, 21.6. Found (percent): C, 48.8; H, 4.7; N, 21.4.

EXAMPLE 2 This example describes the preparation of 3,5-dinitro- 6-methyl-2-aminopyridine and its acetyl derivative.

Five (5) grams of 3-nitro-6-methyl-2-nitroaminopyridine, prepared from the action of nitric acid on S-nitro- G-methyl-Z-aminopyridine, was added to 25 ml. concentrated sulfuric acid. The resultant mixture is heated on a steam bath for 40 minutes yielding a clear yellow solution. After cooling to room temperature, the solution is added to crushed ice and the mixture placed in a refrigerator for two days during which time a solid separated from the solution. The mixture was filtered and the solid washed with a small amount of water. Recrystallization from an ethanol-water mixture yielded a solid melting at Calcd. for C H N O (percent): C, 36.4; H, 3.0; N, 28.3. Found (percent): C, 35.7; H, 3.05; N, 27.2.

Five (5) grams 3,S-dinitro-6-methyl-2-aminopyridine (prepared above) was added to 25 ml. glacial acetic acid and 50 ml. acetic anhydride and the mixture refluxed for 4 /2 hours. After cooling to room temperature the mixture was added to crushed ice and neutralized with solid sodium bicarbonate. The resultant solution was extracted with ether, the ether layers dried over anhydrous magnesium sulfate and the solvent removed by distillation. The residue which was a solid melted at 72-76 C. The solid was recrystallized from ethanolwwater yielding a solid melting at 106-107 C.

Calcd. for C H N O (percent): C, 40.0; H, 3.33; N, 23.3. Found (percent): C, 39.2; H, 3.9; N, 23.03.

EXAMPLE 3 This example describes the preparation of 2,6-dimet-hyl- 3-nitro-4-aminopyridine.

Four (4) grams 4-amino-2,6-dimethylpyridine was dissolved, with stirring, in 20 ml. concentrated sulfuric acid. The resultant mixture was cooled to l C. and then 2.68 ml. concentrated nitric acid slowly added, keeping the temperature between l0 C. and C. The mixture was then stirred at l0 C. to 0 C. for one hour. The mixture was added to crushed ice and made alkaline with ammonia, ammonium carbonate solution. The resultant solution was concentrated to half its volume on a steam bath under reduced pressure, at which time a yellow solid precipitated from the solution. The mixture was cooled to 5 C. and the solid removed by filtration, the solid washed with cold water and dried in a vacum oven at 60 C. The resultant solid melted at 210 C.

One (1) gram 2,6-dimethyl-4-nitroaminopyridine (prepared above) was added to ml. concentrated sulfuric acid and the resultant mixture heated on a steam bath for 1 hour. The mixture was then added to crushed ice and made alkaline, to a pH 8, by the addition of ammonium hydroxide. The resultant solution was placed in a refrigerator overnight during which time, 2,6-dimethyl-3- nitro-4-aminopyridine precipitated as a bulf colored solid having a melting point of ll37 C.

Other compounds prepared according to the procedures outlined above include:

3-nitro-4-aminopyridine S-nitro-Z- aminopyridine 3 ,5 -dinitro-2-aminopyridine 3 ,5 -dinitro-4-aminopyridine 2-chloro-3-nitro-4-aminopyridine 2-chloro-3-nitro-6-aminopyridine 2-chloro-3-nitro-6-acetamidopyridine 2-chloro-5-nitro-4-aminopyridine 3-chloro-5-nitro-6-phenylsulfonamidopyridine 5-chloro-3-nitro-2-acetamidopyridine 6-chloro-3-nitro-2-aminopyridine 6-chloro-5-nitro-2-aminopyridine 2, 6-dichloro-3-nitro-4-aminopyridine 2-iodo-3-nitro-4-aminopyridine 3-methyl-5-nitro-2-aminopyridine 4-methyl-3-nitro-2-aminopyridine 6-methyl-3 -m'tro-2-aminopyridine 6-methyl-5-nitro-2-aminopyridine 4,6-dimethyl-Z,4-nitro-2-aminopyridine 6-n-butyl-3-nitro-2-aminopyridine S-trichloromethyl-3-nitro-2-aminopyridine 4-allyl-3 -nitro-2-aminopyridine 4-ethoxy-3-nitro-2-acetamidopyridine 6-carboethoxy-3-nitro-2-aminopyridine S-nitro-2-dipropylaminopyridine 3 -nitro-4-methanesulfonamidopyridine 2-chloro-3-nitro-4-acetamidopyridinium hydrochloride 2,6-dichloro-3-nitro-4-acetamido-N-methylpyridinium chloride 3-nitro-4-acetamidopyridinium oxalate 3 ,5 -dinitro-2-voleramidopyridine 2-chloro-3-nitro-4-propylsulfonamidopyridine The herbicidal compositions of this invention contain at least one active ingredient and a material referred to in the art as a herbicidal adjuvant in liquid or solid form. The herbicidal compositions are prepared by admixing the active ingredient with an adjuvant including diluents, extenders, carriers and conditioning agents to provide compositions in the form of finely-divided particulate solids, granules, pellets, solutions and aqueous dispersions or emulsions.

Typical finely-divided solid carriers and extenders which can be used in the herbicidal compositions of this invention include but is not limited to talcs, clays, pumice, silica, diatomaceous earth, quartz, fullers earth, powdered cord, powdered wood, walnut flour, chalk, tobacco dust, volcanic ash and the like. Typical liquid diluents include but are not limited to kerosene, Stoddard solvent, hexane, benzene, toluene, acetone, ethylene dichloride, xylene, alcohols, diesel oil, glycols and the like.

The herbicidal compositions of this invention, particularly liquids and wettable particles, usually contain as a conditioning agent one or more surface-active agents in amounts sufiicient to render a given composition readily dispersible in water or in oil. By the term surface-active agent it is understood that wetting-agents, dispersing agents, suspending agents and emulsifying agents are included therein.

The term herbicidal compositions as used herein and in the appended claims is intended to mean not only compositions in a suitable form for application but also concentrated compositions which require dilution or extension with a suitable quantity of liquid or solid adjuvant prior to application.

The term plant system as used herein and in the appended claims means germinantseeds, emerging seedlings and established vegetation including the roots and aboveground portions.

EXAMPLE 4 The pre-emergent herbicidal activity of representative nitroaminopyridines of this invention is demonstrated as follows:

A good grade of top soil is placed in aluminum pans and compacted to a depth of /3 to /2 inch from the top of the pan. A predetermined number of seeds of each of several plant species are placed on top of the soil in the pans. The seeds were covered with soil and the pan leveled. The herbicidal composition is applied by spraying the surface of the top layer of soil with a solution containing a sufiicient amount of active ingredient to obtain a rate of application of 10 pounds per acre. The pans are then watered from the bottom and placed on a Wet sand bench and maintained for approximately 14 days under ordinary conditions of sunlight and watering. The plants are observed at the end of approximately 14 days and the results recorded. The herbicidal activity index is based on the average percent germination of each seed lot. The activity index is converted to a relative numerical scale for the sake of brevity and simplicity. The results are recorded in Table I.

The pre-emergent herbicidal activity used in the following example is defined as follows.

N0te.-Componnd (A), fi-rnethy1-5-nitro-2-aminopyridine; Compound (1}), 2-chloro-3-n1tro6-acetamidopyridil1c; Compound (0), 5-chloro-3- urtro-Q-acetamidopy ridine.

EXAMPLE 5 This example demonstrates the post-emergent herbicidal activity of representative nitroaminopyridines of this invention.

The active ingredient is applied in spray form to 14-day old specimens of the same plant species used in the preemergent tests above. The herbicidal sprays are acetonewater solutions containing 0.5% active ingredient. The solutions are applied at a rate equal to approximately pounds per acre of active ingredient. The treated plants are placed in a greenhouse and the effects observed and recorded after approximately 14 days. The results are recorded in Table H.

The post-emergent herbicidal activity index used in this example is based on the average percent injury of each plant species and is defined as follows.

As mentioned hereinbefore the herbicidal compositions of this invention comprise an active ingredient and one or more herbicidal adjuvants which can be solid or liquid extenders, carriers, diluents, conditioning agents and the like. Preferred herbicidal compositions containing the active ingredients of this invention have been developed so that the active ingredients can be used to the greatest advantage to modify the growth of plant systems in soil. The preferred compositions comprise certain Wettable powders, aqueous suspensions, dust formulations, granules, emulsifiable oils and solutions in solvents. In general these preferred compositions can all contain one or more surface-active agents.

Surface-active agents which can be used in the herbicidal compositions of this invention are set out, for example, in Searle U.S. Pat. 2,426,417, Todd U.S. Pat. 2,655,447, Jones U.S. Pat. 2,412,510 and Lenher U.S. Pat. 2,139,276. A detailed list of such agents is also set forth by J. W. McCutcheon in Soap and Chemical Specialties, November 1947, page 8011 et seq., entitled Synthetic Detergents; Detergents and Emulsifiers-Up to Date (1960) by I. W. McCutcheon, Inc., and Bulletin E106 of the Bureau of Entomology and Plant Quarantine of the U.S.D.A. In general less than 15 parts by weight of the surface-active agent is present per 100 parts by weight of the herbicidal composition.

Wettable powders are water-dispersable compositions containing one or more active ingredients, an inert solid extender and one or more wetting and dispersing agents. The inert solid extenders are usually of mineral origin such as the natural clays, diatomaceous earth and synthetic minerals derived from silica and silicate. Examples of such extenders include kaolinites, attapulgite clay and synthetic magnesium silicate.

Preferred wetting agents are alkyl benzene and alkyi naphthalene sulfonates, sulfated fatty alcohols, amines or acid amides, long chain acid esters of sodium isothionate, esters of sodium sulfosuccinate, sulfated or sulfonated fatty acid esters, petroleum sulfonates, sulfonated vegetable oils and ditertiary acetylinic glycols. Preferred dispersants are methyl cellulose, polyvinyl alcohols, sodium lignin sulfonates, polymeric alkyl naphthalene sulfonates, sodium naphthalene sulfonate, polymethylene bisnaphthalenesulfonate and sodium N-methyl-N-(long chain acid) taurates.

The Wettable powder compositions of this invention usually contain from about 5 to about parts of active ingredient, from about 0.25 to about 3.0 parts of Wetting agent, from about 0.25 to about 7 parts of dispersant and from about 4.5 to about 94.5 parts of inert solid extender, all parts being by weight of the total composition. Where required from about 0.1 to 2.0 parts by weight of the solid inert extender can be replaced by a corrosion inhibitor or anti-foaming agent or both.

Aqueous suspensions are usually prepared by mixing together an aqueous slurry of Water-insoluble active ingredient in the presence of dispersing agents to obtain a concentrated slurry of very finely-divided particles. The resulting concentrated aqueous suspension is characterized by its extremely small particle size, so that when diluted and sprayed coverage is very uniform.

Dusts are dense finely-divided particulate compositions which are intended for application to the soil in dry form. Dusts are characterized by their free-flowing and rapid settling properties so that they are not readily wind-borne to areas Where they are of no value. Dusts contain primarily an active ingredient and a dense, free-flowing, finely-divided particulate extender. However, their performance is sometimes aided by the inclusion of a wetting agent such as those listed hereinbefore under Wettable powder compositions and convenience in manufacture frequently demands the inclusion of an inert, absorptive grinding aid. Suitable class of grinding aids are natural clays, diatomaceous earth and synthetic minerals derived from silica or silicate. Preferred grinding aids include attapulgite clay, diatomaceous silica, synthetic fine silica and synthetic calcium and magnesium silicates.

The inert finely-divided solid extender for the dusts can be of vegetable or mineral origin. The solid extenders are characterized by possessing relatively low surface areas and are poor in liquid absorption. Suitable inert solid extenders for herbicidal dusts include micaceous talcs, pyrophyllite, dense kaolin clays, ground calcium phosphate rock and tobacco dust. The dusts usually contain from about 0.5 to 99 parts active ingredient, 0- to 50 parts grinding aid, 0 to 3 parts wetting agent and 1 to 99.5 parts dense solid extender, all parts being by weight based on the total weight of the dust.

The Wettable powders described above may also be used in the preparation of dusts. While such Wettable powders could be used directly in dust form, it is more advantageous to dilute them by blending With the dense dust diluent. In this manner, dispersing agents, corrosion inhibitors, and anti-foam agents may also be found as components of a dust.

Emulsifiable oils are usually solutions of active ingredient in Water-immiscible solvents together with a surfactant. Suitable solvents for the active ingredient of this invention include hydrocarbons and water-immiscible ethers, esters or ketones. Suitable surfactants are anionic, cationic and non-ionic such as alkyl aryl polyethoxy alcohols, alkyl and alkyl aryl polyether alcohols, polyethylene glycol fatty esters, fatty alkyllol amide condensates, amine salts of fatty alcohol sulfates together with long chain alcohols and oil soluble petroleum sulfonates or mixtures thereof. The emulsifiable oil compositions generally contain from about 5 to 95 parts active ingredient, about 1 to 10 parts surfactant and about 4 to 94 parts solvent, all parts being by Weight based on the total weight of emulsifiable oil.

Granules are physically stable particulate compositions comprising active ingredient adhering to or distributed through a basic matrix of an inert, finely-divided particulate extender. In order to aid leaching of the active ingredient from the particulate, a surfactant such as those listed hereinbefore under wettable powders can be present in the composition. Natural clays, pyrophyllites and vermiculite are examples of operable classes of particulate mineral extenders. The preferred extenders are the porous, absorptive, preformed particles such as preformed and screened particulate attapulgite or heat expended, particulate vermiculite, and the finely-divided clays such as kaolin clays, hydrated attapulgite or bentonitic clays. These extenders are sprayed or blended with the active ingredient to form the herbicidal granules.

The mineral particles which are used in the granular herbicidal compositions of this invention usually have a size range of 10 to 100 mesh, but preferably such that a large majority of the particles have from 14 to 60 mesh with the optimum size being from 20 to 40 mesh. Clay having substantially all particles between 14 and 80 mesh and at least about 80 percent between 20 and 40 mesh is particularly preferred for use in the present granular compositions. The term mesh as used herein means U.S. Sieve Series.

The granular herbicidal compositions of this invention generally contain from about 1 part to about 30 parts by weight of nitroaminopyridine per 100 parts by weight of clay and to about parts by weight of wetting agent per 100 parts by weight of clay. The preferred herbicidal granular compositions contain from about 5 parts to about 25 parts by weight of active ingredient per 100 parts by weight of clay.

The herbicidal compositions of this invention can also contain other additaments, for example, fertilizers, other herbicides, pesticides and the like, used as adjuvant or in combination with any of the above-described adjuvants.

The compounds of this invention may be used in combination with known herbicides in order to provide enhanced biological effectiveness. The use of various herbicides in combination at the time of a single application or sequentially is common in practice. Herbicides which may be used in combination with the compounds of this invention include but are not limited to: substituted phenoxyaliphatic acids such as 2,4-dichlorophenoxyacetic acid; 2,4,S-trichlorophenoxyacetic acid, 2-methyl-4-chlorophenoxyacetic acid and the salts, esters and amides thereof; triazine derivatives, such as 2-chloro-4-ethylamino-6-isopropylamino-s-triazine; 2,4 bis( (isopropylamino) 6Fmethoxy-s-triazine and 2-methylmercapto-5,6-bis(isopropylamino)-s-triazine; urea derivaties such as 3-(3,4-dichlorophenyl) 1,1 dimethylurea and 3 (m-trifluoromethylphenyl)-1,1-dimethylurea and 3-(3,4-dichlorophenyl)-1- methoxy-l-methylurea; pyridylium derivatives such as 1:l-ethylene-2,Z-dipyridylium dihalide; acetanilides such as N-isopropyl-alpha-chloroacetanilide, and 2-chloro-2', 6'-diethyl-N-methoxymethyl acetanilide; acetamides such as N,N-diallyl-alphachloroacetamide, carbamates such as ethyl-N,N-di-n-propylthiolcarbamate, and 2,3 dichloroallyl diisopropylthiolcarbamate; substituted uracils such as S-bromo-3-sec-butyl-6-methyluracil, substituted anilines such as N,N dipropyl-alpha,alpha,alpha-trifiuoro-Z,6-dinitro-p-toluidine; pyridazone derivatives such as S-amino- 4-chloro-2-phenyl-3-(2H)-pyridazinone, and the like.

Fertilizers useful in combination with the active ingredients include, for example ammonium nitrate, urea and superphosphate. Other useful additaments include materials in which plant organisms take root and grow such as compost, manure, humus, sand and the like.

When operating in accordance with the present invention, eifective amounts of the nitroaminopyridines are dispersed on or in the soil or plant growth media and applied to plant systems in any convenient fashion. Application to the soil or growth media can be carried out by simply mixing with the media, by applying to the surface of the soil and thereafter dragging or discing into the soil to the desired depth, or by employing a liquid carrier to accomplish the penetration and impregnation.

The application of liquid and particulate solid herbicidal compositions to the surface of soil or to plant systems can be carried out by conventional methods, e.g., power dusters, boom and hand sprayers and spray dusters. The compositions can also be applied from airplanes as a dust or a spray because of their effectiveness at low dosages. In a further method, the distribution of the active ingredients in soil can be carried out by admixture with the water employed to irrigate the soil. In such procedures, the amount of water can be varied with the porosity and water holding capacity of the soil to obtain the desired depth of distribution of the active ingredient.

The application of an effective or hebicidal amount of the nitroaminopyridines to the soil or growth media or plant systems is essential and critical for the practice of one embodiment of the present invention. The exact amount of active ingredient to be employed is dependent upon the response desired in the plant as well as such other factors as the plant species and stage of development thereof, the specific soil and depth at which the active ingredients are distributed in the soil and the amount of rainfall as well as the specific nitroaminopyridine employed. In foliar treatment for the control or modification of vegetative growth, the active ingredients are applied in amounts from about 1 to about or more pounds per acre. In applications to soil for the control or modification of the growth of germinant seeds, emerg ing seedlings and established vegetation, the active ingredients are applied in amounts from about 1 to about 50 or more pounds per acre. In selective pre-emergent herbicidal applications the nitroaminopyridines are usually applied in amounts from 0.1 to 5 pounds per acre. It is believed that one skilled in the art can readily determine from this specification, including examples, the application. rate for any specific situation.

The terms soil and growth media are employed in the present specification and claims in their broadest sense to be inclusive of all conventional soils as defined in Websters New International Dictionary, Second Edition, Unabridged (1961). Thus, the terms refer to any substance or media in which vegetation may take root and grow, and are intended to include not only earth but compost, manure, muck, humus, sand and the like, adapted to support plant growth.

While the illustrative embodiments of the invention have been described hereinbefore with particularity, it will be understood that various other modifications will be apparent to and can readily be made by those skilled in the art without departing from the scope and spirit of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and description set forth herein but rather the claims be construed as encompassing all the features of patentable novelty which reside in the present invention including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.

What is claimed is:

1. A compound of the formula wherein R is alkyl having a maximum of four carbon atoms; R is alkanoyl having a maximum of six carbon atoms, alkylsulfonyl having a maximum of four carbon atoms and phenylsulfonyl; n and x are each integers l to 2 and provided that at least one of n or x is 2.

d2. The compound 3,5-dinitro-6-methyl-Z-acetamidopyr- 1 me.

3. The compound 2,6-dimethy1-3-nitro-4-aminopyridine. Chem. Abstracts II, v01. 58, pages 13909-13910 (1963).

Chem. Abstracts III, vol. 59, pages 1148641487 References Cited (1963). UNITED STATES PATENTS ,495,969 2/1970 Driscoll 71 94 5 A N L ROTMAN Pnmary Exammer OTHER REFERENCES Chem. Abstracts (I), v01. 64, pages 19618-19619 71-94; 260-294.8 F, 295.5 A, 296R (1966). 

